With the football season upon us once again, I’ve decided to blog about an all-too-common injury we see in competitive athletes and the rehabilitation following surgery. ACL ruptures are usually followed by reconstruction surgery that is then followed by progressive rehabilitation that may last up to 12 months. In the NFL, there is an average of 53 ACL injuries per year. Offensive skill positions, such as running backs & wide receivers, have the highest ACL injury rates. Depending on the extent of injury to these athletes, most players can expect 6-12 months before being cleared by a physician to return to their previous level of play.

If you’re a fan of the New England Patriots, you’ve probably heard of the comeback of receiver Wes Welker from ACL reconstructive surgery very closely. Welker tore his ACL at the end of the 2009-2010 season in January of 2010, and then started Game 1 of the 2010-2011 NFL season in September 2010. In many athletes who experience ACL injury, we often get asked the question how can Wes Welker return to professional football so soon, but I can’t?!?

Welker’s comeback has definitely pushed conventional time limits for his return to the sport. Most people who undergo reconstructive knee surgery can return to athletic activities at six to eight months, but they’re usually not back to their previous level of competition until one year. Keep in mind—we’re not talking about recreational sports; this is the NFL.Professional athletes take the human body to the limits of what it can do, and so we learn from them. Ultimately, we often want to emulate them, which is why it’s important to put Welker’s comeback into perspective.

We attempt to stress to athletes with ACL injuries that the average pro football player takes 54 weeks to return to play after an ACL injury. When a patient tries to return earlier, they often experience pain and swelling, and are at some level of increased risk of re-injury.

Another thing for athletes to keep in mind is that most NFL players who sustain an injury to their ACL do typically return to play again in the NFL, however a research study from the American Journal of Sports Medicine has shown that most athletes return with diminished performance on the field.

James L. Carey, MD and colleagues from the Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA conducted a study that objectively measure an NFL player's performance before and after an ACL injury. (Dr. Carey is now affiliated with Vanderbilt Sports Medicine, Nashville, Tenn.)

The researchers collected data on ACL injuries sustained by NFL running backs (RBs) and wide receivers (WRs) during a five-year period (1998-2002). This data came from NFL game summaries, play-by-play documents, weekly injury reports, and player profiles. The injury group was compared to a control group consisting of all NFL RBs and WRs without an identified ACL injury who played during the 2000 season.

In this study, game performance output in the professional athlete was the measurement used to objectify the data. A "power rating" was assigned for every player in every season, defined as a weighted sum of total yards and touchdowns, likely the most important statistics of RB and WR performance. The power ratings for the 3 seasons prior to ACL injury were compared to the power ratings for the 3 seasons following ACL injury.

Data were analyzed for 31 players with 33 ACL injuries. Of the injured players, 21% (7 of 33 ACL injuries) never returned to play in another regular season NFL game. Of the 795 that did return, most players returned to action 9 to 12 months after an ACL injury.

For those players who returned to NFL action following an ACL injury, performance fell by 1/3. Power rating per game played decreased from 9.9 pre-injury to 6.5 post-injury. This decline in player production was statistically significant when compared to the 146 players in the control group.

Knee pain, stiffness, loss of strength, deconditioning and reduced proprioception (the sense of knowing where your leg is) may be factors explaining the loss of production in players after an ACL injury, the authors theorize. Further, ACL reconstruction does not perfectly recreate the complex anatomy and composition of a person's ACL before injury.

An important note to take into consideration with this study was that prior to their injury the ACL-injured players performed better than the controls did. "High-performance RBs and WRs are more likely to be injured because they compete in more plays per game, carry the ball longer on each play, and attract more defensive attention," the authors say. "The same qualities of RBs and WRs that contribute to high performance -- instantaneous decelerations as well as explosive pivoting and cutting maneuvers -- may increase the risk for ACL injury."

The researchers cite a recent survey of all 31 NFL team physicians who were asked to quantify "what percentage of players return to play in the NFL after ACL reconstruction." Ninety % of team physicians responded "90 to 100%" of players (assuming not borderline talent) return to the NFL. The current study found the number of players who return to play after an ACL injury was actually less, at 79%.

"Most studies report good to excellent results in the majority of ACL reconstructions regardless of technique or patient age, but the professional football player presents unique demands on the reconstructed knee," "Our findings may be useful for athletes, coaches, and team owners in anticipating the future contributions of a player who has injured an ACL."

This study also helps to more objectively put into perspective that while Welker did succeed in his return to the NFL, and in fact contribute another valuable season to Tom Brady and the Patriots of 2010-2011, his determination should be praised; however, that doesn’t mean his quick comeback is plausible for all patients.